8

SY58013U

Micrel, Inc.

M9999-020207

hbwhelp@micrel.com or (408) 955-1690

R2

82

Ω

R2

82

Ω

+3.3V

+3.3V

R1

130

Ω

R1

130

Ω

+3.3V

Figure 5. Parallel Termination–Thevenin Equivalent

Note 1.

For +2.5V systems: R1 = 250

Ω, R2 = 62.5Ω

Note 2.

For +3.3V systems: R1 = 130

Ω, R2 = 82Ω

Z = 50

Ω

Z = 50

Ω

50

Ω

50

Ω

50

Ω

+3.3V

+3.3V

source

destination

Rb

C1

0.01

µF

(optional)

Figure 6. Three-Resistor “Y–Termination”

Note 1.

Power-saving alternative to Thevenin termination.

Note 2.

Place termination resistors as close to destination inputs as possible.

Note 3.

Note 4.

C1 is an optional bypass capacitor intended to compensate for any

OUTPUT TERMINATION RECOMMENDATIONS

LVPECL outputs have very low output impedance (open

emitter), and small signal swing which results in low EMI

(electro-magnetic interference). The LVPECL is ideal for

driving 50

Ω and 100Ω controlled impedance transmission

lines. In addition, LVPECL is compatible for driving standard

PECL inputs since PECL inputs require only 100mV input

swing. Further, there are several techniques in terminating

the LVPECL outputs, as shown in Figure 5 through 7.

+3.3V

+3.3V

R2

82

Ω

+3.3V

+3.3V

R1

130

Ω

R1

130

Ω

R2

82

Ω

Q

/Q

R4

1k

Ω

R3

1.6k

Ω

Figure 7. Terminating Unused I/O

Note 1.

Unused output (/Q) must be terminated to balance the output.

Note 2.

For +2.5V systems: R1 = 250

Ω, R2 = 62.5Ω, R3 = 1.25kΩ,

R4 = 1.2k

Ω.

For +3.3V systems: R1 = 130

Ω, R2 = 82Ω, R3 = 1kΩ, R4 = 1.6kΩ.

Note 3.

Unused output pairs (Q and /Q) may be left floating.

Part Number

Function

Data Sheet Link

SY58011U

7GHz, 1:2 CML Fanout Buffer/Translator

http://www.micrel.com/product-info/prod/ucts/sy58011u.shtml

With Internal I/O Termination

SY58012U

5GHz, 1:2 LVPECL Fanout Buffer/Translator With

http://www.micrel.com/product-info/products/sy58012u.shtml

Internal Input Termination

SY58013U

6GHz, 1:2 Fanout Buffer/Translator w/400mV

http://www.micrel.com/product-info/products/sy58013u.shtml

LVPECL Outputs and Internal Input Termination

16-MLF™ Manufacturing Guidelines

www.amkor.com/products/notes_papers/MLF_AppNote_0902.pdf

Exposed Pad Application Note

M-0317

HBW Solutions

http://www.micrel.com/product-info/as/solutions.shtml

RELATED MICREL PRODUCTS AND SUPPORT DOCUMENTATION